package com.lanchetech.service;


import org.springframework.stereotype.Service;

import java.util.Map;
import java.util.function.Function;
import java.util.stream.Stream;

@Service
public class PlaceholderResolver {
    /**
     * 默认前缀占位符
     */

    public static final String DEFAULT_PLACEHOLDER_PREFIX = "${";

    /**
     * 默认后缀占位符
     */

    public static final String DEFAULT_PLACEHOLDER_SUFFIX = "}";

    /**
     * 默认单例解析器
     */

    private static PlaceholderResolver defaultResolver = new PlaceholderResolver();

    /**
     * 占位符前缀
     */

    private String placeholderPrefix = DEFAULT_PLACEHOLDER_PREFIX;

    /**
     * 占位符后缀
     */

    private String placeholderSuffix = DEFAULT_PLACEHOLDER_SUFFIX;

    private PlaceholderResolver() {

    }

    private PlaceholderResolver(String placeholderPrefix, String placeholderSuffix) {
        this.placeholderPrefix = placeholderPrefix;

        this.placeholderSuffix = placeholderSuffix;

    }

    /**
     * 获取默认的占位符解析器，即占位符前缀为"${", 后缀为"}"
     *
     * @return
     */

    public static PlaceholderResolver getDefaultResolver() {
        return defaultResolver;

    }

    public static PlaceholderResolver getResolver(String placeholderPrefix, String placeholderSuffix) {
        return new PlaceholderResolver(placeholderPrefix, placeholderSuffix);

    }

    /**
     * 解析带有指定占位符的模板字符串，默认占位符为前缀：${ 后缀：}
     * <p>
     * 如：template = category:${}:product:${}
     * <p>
     * values = {"1", "2"}
     * <p>
     * 返回 category:1:product:2
     *
     * @param content 要解析的带有占位符的模板字符串
     * @param values  按照模板占位符索引位置设置对应的值
     * @return
     */

    public String resolve(String content, String... values) {
        int start = content.indexOf(this.placeholderPrefix);

        if (start == -1) {
            return content;

        }

//值索引

        int valueIndex = 0;

        StringBuilder result = new StringBuilder(content);

        while (start != -1) {
            int end = result.indexOf(this.placeholderSuffix);

            String replaceContent = values[valueIndex++];

            result.replace(start, end + this.placeholderSuffix.length(), replaceContent);

            start = result.indexOf(this.placeholderPrefix, start + replaceContent.length());

        }

        return result.toString();

    }

    /**
     * 解析带有指定占位符的模板字符串，默认占位符为前缀：${ 后缀：}
     * <p>
     * 如：template = category:${}:product:${}
     * <p>
     * values = {"1", "2"}
     * <p>
     * 返回 category:1:product:2
     *
     * @param content 要解析的带有占位符的模板字符串
     * @param values  按照模板占位符索引位置设置对应的值
     * @return
     */

    public String resolve(String content, Object[] values) {
        return resolve(content, Stream.of(values).map(String::valueOf).toArray(String[]::new));

    }

    /**
     * 根据替换规则来替换指定模板中的占位符值
     *
     * @param content 要解析的字符串
     * @param rule    解析规则回调
     * @return
     */

    public String resolveByRule(String content, Function rule) {
        int start = content.indexOf(this.placeholderPrefix);

        if (start == -1) {
            return content;

        }

        StringBuilder result = new StringBuilder(content);

        while (start != -1) {
            int end = result.indexOf(this.placeholderSuffix, start);

//获取占位符属性值，如${id}, 即获取id

            String placeholder = result.substring(start + this.placeholderPrefix.length(), end);

//替换整个占位符内容，即将${id}值替换为替换规则回调中的内容

            String replaceContent = placeholder.trim().isEmpty() ? "" : (String) rule.apply(placeholder);

            result.replace(start, end + this.placeholderSuffix.length(), replaceContent);

            start = result.indexOf(this.placeholderPrefix, start + replaceContent.length());

        }

        return result.toString();

    }

    /**
     * 替换模板中占位符内容，占位符的内容即为map key对应的值，key为占位符中的内容。
     * <p>
     * 如：content = product:${id}:detail:${did}
     * <p>
     * valueMap = id -> 1; pid -> 2
     * <p>
     * 经过解析返回 product:1:detail:2
     *
     * @param content  模板内容。
     * @param valueMap 值映射
     * @return 替换完成后的字符串。
     */

    public String resolveByMap(String content, final Map valueMap) {
        return resolveByRule(content, placeholderValue -> String.valueOf(valueMap.get(placeholderValue)));

    }

}
